[PATCH net] net: phy: realtek: fix rtl8211e rx/tx delay config

[PATCH net] net: phy: realtek: fix rtl8211e rx/tx delay config

[Willy Liu]

There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
delays to TXC and RXC for TXD/RXD latching. These two pins can config via
4.7k-ohm resistor to 3.3V hw setting, but also config via software setting
(extension page 0xa4 register 0x1c bit13 12 and 11).

The configuration register definitions from table 13 official PHY datasheet:
PHYAD[2:0] = PHY Address
AN[1:0] = Auto-Negotiation
Mode = Interface Mode Select
RX Delay = RX Delay
TX Delay = TX Delay
SELRGV = RGMII/GMII Selection

This table describes how to config these hw pins via external pull-high or pull-
low resistor.

It is a misunderstanding that mapping it as register bits below:
8:6 = PHY Address
5:4 = Auto-Negotiation
3 = Interface Mode Select
2 = RX Delay
1 = TX Delay
0 = SELRGV
So I removed these descriptions above and add related settings as below:
14 = reserved
13 = force Tx RX Delay controlled by bit12 bit11
12 = Tx Delay
11 = Rx Delay
10:0 = Test && debug settings reserved by realtek

Test && debug settings are not recommend to modify by default.

Fixes: f81dadbcf7fd ("net: phy: realtek: Add rtl8211e rx/tx delays config")
Signed-off-by: Willy Liu <willy.liu@realtek.com>
---
 drivers/net/phy/realtek.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)
 mode change 100644 => 100755 drivers/net/phy/realtek.c

diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
old mode 100644
new mode 100755
index 95dbe5e..f5fce80
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -32,9 +32,9 @@
 #define RTL8211F_TX_DELAY			BIT(8)
 #define RTL8211F_RX_DELAY			BIT(3)
 
-#define RTL8211E_TX_DELAY			BIT(1)
-#define RTL8211E_RX_DELAY			BIT(2)
-#define RTL8211E_MODE_MII_GMII			BIT(3)
+#define RTL8211E_CTRL_DELAY			BIT(13)
+#define RTL8211E_TX_DELAY			BIT(12)
+#define RTL8211E_RX_DELAY			BIT(11)
 
 #define RTL8201F_ISR				0x1e
 #define RTL8201F_IER				0x13
@@ -249,13 +249,13 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 		val = 0;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_ID:
-		val = RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_RXID:
-		val = RTL8211E_RX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_RX_DELAY;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_TXID:
-		val = RTL8211E_TX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_TX_DELAY;
 		break;
 	default: /* the rest of the modes imply leaving delays as is. */
 		return 0;
@@ -263,11 +263,12 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 
 	/* According to a sample driver there is a 0x1c config register on the
 	 * 0xa4 extension page (0x7) layout. It can be used to disable/enable
-	 * the RX/TX delays otherwise controlled by RXDLY/TXDLY pins. It can
-	 * also be used to customize the whole configuration register:
-	 * 8:6 = PHY Address, 5:4 = Auto-Negotiation, 3 = Interface Mode Select,
-	 * 2 = RX Delay, 1 = TX Delay, 0 = SELRGV (see original PHY datasheet
-	 * for details).
+	 * the RX/TX delays otherwise controlled by RXDLY/TXDLY pins. 
+	 * The configuration register definition:
+	 * 14 = reserved
+	 * 13 = Force Tx RX Delay controlled by bit12 bit11,
+	 * 12 = RX Delay, 11 = TX Delay
+	 * 10:0 = Test && debug settings reserved by realtek
 	 */
 	oldpage = phy_select_page(phydev, 0x7);
 	if (oldpage < 0)
@@ -277,7 +278,8 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 	if (ret)
 		goto err_restore_page;
 
-	ret = __phy_modify(phydev, 0x1c, RTL8211E_TX_DELAY | RTL8211E_RX_DELAY,
+	ret = __phy_modify(phydev, 0x1c, RTL8211E_CTRL_DELAY
+			   | RTL8211E_TX_DELAY | RTL8211E_RX_DELAY,
 			   val);
 
 err_restore_page:
-- 
1.9.1

Re: [PATCH net] net: phy: realtek: fix rtl8211e rx/tx delay config

[Andrew Lunn]

On Fri, Sep 25, 2020 at 03:25:15PM +0800, Willy Liu wrote:
> There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
> delays to TXC and RXC for TXD/RXD latching. These two pins can config via
> 4.7k-ohm resistor to 3.3V hw setting, but also config via software setting
> (extension page 0xa4 register 0x1c bit13 12 and 11).
> 
> The configuration register definitions from table 13 official PHY datasheet:
> PHYAD[2:0] = PHY Address
> AN[1:0] = Auto-Negotiation
> Mode = Interface Mode Select
> RX Delay = RX Delay
> TX Delay = TX Delay
> SELRGV = RGMII/GMII Selection
> 
> This table describes how to config these hw pins via external pull-high or pull-
> low resistor.
> 
> It is a misunderstanding that mapping it as register bits below:
> 8:6 = PHY Address
> 5:4 = Auto-Negotiation
> 3 = Interface Mode Select
> 2 = RX Delay
> 1 = TX Delay
> 0 = SELRGV
> So I removed these descriptions above and add related settings as below:
> 14 = reserved
> 13 = force Tx RX Delay controlled by bit12 bit11
> 12 = Tx Delay
> 11 = Rx Delay
> 10:0 = Test && debug settings reserved by realtek

Hi Willy

Thanks for adding a full description of what the bits do.

Please in future add a version number to the subject line.

[PATCH net v3] .....

So we know which is the latest version.

I think the fix is actually wrong.

        /* enable TX/RX delay for rgmii-* modes, and disable them for rgmii. */
        switch (phydev->interface) {
        case PHY_INTERFACE_MODE_RGMII:
                val = 0;
                break;
        case PHY_INTERFACE_MODE_RGMII_ID:
                val = RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
                break;
        case PHY_INTERFACE_MODE_RGMII_RXID:
                val = RTL8211E_RX_DELAY;
                break;
        case PHY_INTERFACE_MODE_RGMII_TXID:
                val = RTL8211E_TX_DELAY;
                break;
        default: /* the rest of the modes imply leaving delays as is. */
                return 0;
        }

If the user requests RGMII, we really should set it to RGMII, not
leave the strapping configuration enabled. That means we need to turn
on the force bit, and the two delays off. Please also change the
case PHY_INTERFACE_MODE_RGMII.

Thanks
	Andrew

Re: [PATCH net] net: phy: realtek: fix rtl8211e rx/tx delay config

[Jakub Kicinski]

On Fri, 25 Sep 2020 15:25:15 +0800 Willy Liu wrote:
> There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
> delays to TXC and RXC for TXD/RXD latching. These two pins can config via
> 4.7k-ohm resistor to 3.3V hw setting, but also config via software setting
> (extension page 0xa4 register 0x1c bit13 12 and 11).
> 
> The configuration register definitions from table 13 official PHY datasheet:
> PHYAD[2:0] = PHY Address
> AN[1:0] = Auto-Negotiation
> Mode = Interface Mode Select
> RX Delay = RX Delay
> TX Delay = TX Delay
> SELRGV = RGMII/GMII Selection

Checkpatch says:

ERROR: do not set execute permissions for source files
#48: FILE: drivers/net/phy/realtek.c

ERROR: trailing whitespace
#91: FILE: drivers/net/phy/realtek.c:266:
+^I * the RX/TX delays otherwise controlled by RXDLY/TXDLY pins. $

total: 2 errors, 0 warnings, 0 checks, 54 lines checked